O’Donnell was invited to write a novelization of the 1966 film. The novel, released a year before the film itself, and based on his original screenplay for the movie, fared considerably better than the film. During the following decades he would write a total of eleven Modesty Blaise novels and two collections of short stories. Several of the short stories either adapt comic strip stories, or would later be adapted into comic strip stories themselves. Characters cross over between the two media. Except for „Pieces of Modesty“, the books were originally issued in hardback and have subsequently gone through numerous paperback editions.

1965 Modesty Blaise
1966 Sabre-Tooth
1967 I, Lucifer
1969 A Taste for Death
1971 The Impossible Virgin
1972 Pieces of Modesty (Short stories)
1973 The Silver Mistress1
1976 Last Day in Limbo
1978 Dragon’s Claw
1981 The Xanadu Talisman
1982 The Night of Morningstar
1985 Dead Man’s Handle
1996 Cobra Trap (Short stories)

O’Donnell’s final book, Cobra Trap, is a short story collection. Intended by O’Donnell to be his literary finale, the final story depicts the deaths of Modesty and Willie (with an implied afterlife). O’Donnell, however, would continue to write the comic strip for several more years, and chose to end it on a more optimistic note, though the comic strip’s finale does not contradict the prose version.

Beginning in the early 2000s (decade), Souvenir Press began a series of paperback reprints of the Modesty Blaise book series, using the first edition hardback covers, and originally concluding with a reprint of Cobra Trap in 2006. Souvenir subsequently gained the rights to the short story collection Pieces of Modesty and issued their reprint of that book in March 2010, with a new cover design based on the original hardback cover from the first Modesty novel, at which point all the Blaise books fell under the same UK publisher for the first time.

In 2008, Penguin Books of India reprinted the full series.

The 2012 Charles Stross book The Apocalypse Codex is, according to the author, a tribute to Modesty Blaise.